Method for determining textile lap weights



May 15, 1962 c. F. STRANDBERG 3,035,226

METHOD FOR DETERMINING TEXTILE LAP WEIGHTS Filed Nov. 17, 1954 TR RE (Poun as or warn) Z 7 REonm Z5 an OFF ovens-r:

INVENTOR ffidf/es Whine Aer BY %/44m4m ATTORNEY United States Patent 9 3,035,226 METHOD FOR DETERMINING TEXTILE LAP WEIGHTS Charles F. Strandherg, Greensboro, NC, assignor to Strandherg Engineering Laboratories, Inc., Greensboro,

' Filed Nov. 11, 1954, Ser. No. 469,496

1 Claim. Cl. 324-65) The invention relates to an improved method for determining textile picker lap weights, and more particularly to a method for determining the amount of moisture contained in moving textile laps in which a device known in the textile art as a rake, which continues to perform its normal function in its relation to the well known picker machine, is also used for making intimate electrical contact with a lap whose moisture content is to be measured, and through such contact variations are imparted to an electrical circuit, which variations are measured by a suitable electrical conductivity indicating device included in such circuit, such as is disclosed for example in Patent No. 1,826,247.

The rake or split-lap preventer, an existing part of the picker, does not contact the surface. Instead, it penetrates or depresses deeply into the lap, thus providing measurement which is not influenced by surface moisture. Additionally, the lap is not a web in the sense that it is not a continuous sheet. It is a bat-like body of raw cotton. At this point it has not been spun and is therefore not similar to warp yarn, fabric, or anything which can be considered a continuous sheet or web.

Weight uniformity of textile laps is essential to good carding and the subsequent production of good yarn. A good deal of etfort has been expended in increasing the uniformity of weight of laps, but uniform weight is dependent fundamentally upon the precision of weight control incorporated in the picker machine and upon the moisture content of the raw material.

In every lap that comes from the picker a portion of its weight is actual cotton and a portion is water. The proportion of each varies with the humidity conditions prevailing at the place the cotton was last stored for a time long enough to permit moisture equilibrium to occur. If the relative humidity has been high, the proportionate amount of Water becomes high with respect to the amount of cotton.

Thus, even though the gross weight per lap is kept constant by good picking, the amount of cotton per lap is Variable and is dependent upon moisture.

Two laps of cotton may weigh exactly the same as they come from the picker, but if one was run when the humidity was high and the other was run when the humidity was low, the first lap will contain less cotton and more water than the second one. Suppose these two laps are put side by side in the card room. Depending upon the relative humidity of the room, one will absorb moisture and become heavier and the other will dry out and become lighter. Thus the two laps no longer weigh the same under the same conditions, and therefore the sliver made from them will lack uniformity.

For example, assume that the standard weight of the picker lap when dofied is 45 pounds, which means 45 pounds of cotton and water. Any lap varying more than one-half of one pound from the standard is rejected. Suppose one lap is dotted at seven o'clock in the morning when it is cool and a heavy dew or shower has raised the humidity. The relative humidity is 71% and the moisture regain in cotton is 8%. This means that there is approximately 3.6 pounds of water and 41.4 pounds of cotton in the lap. During the afternoon the sun is hot, a dry Wind is blowing, and the relative humidity drops to 44%. The regain becomes 6%. The lap dotted at that time is also made to weigh 45 pounds, but the proportion of water and cotton has changed. This lap contains approximately 2.6 pounds of Water and 42.4 pounds of cotton. The lap run in the afternoon contains 1 pound more cotton than the lap run in the mornmg.

Suppose both laps are set aside in the card room where the regain is 8%. The lap which was run at 8% will remain in equilibrium, but the lap which was run at 6% will gain moisture to reach equilibrium at 8%. This additional 2% will cause the lap to weigh 0.9 pound too much. However, laps which differ from the standard by as much as 0.5 pound are being rejected.

There has been some controversy over the accuracy of the two methods employed in the past to overcome this variation in the weight of lap due to moisture.

One method is in the maintenance of constant picker room humidity conditions. It cannot be said that this does not ofier improvement to the picker operation in general, but it is obviously inefiective in maintaining constant regain in raw cotton of variable regain, entering the picker machine, being made into a lap, doffed, and weighed, all within a few minutes. Cotton is characteristically very hygroscopic, but this does not mean that a mass of cotton of one regain will reach a new weight equilibrium immediately upon being exposed to new regain conditions. The time element for loosely packed cotton to tightly packed cotton is a few hours to several Weeks.

The other method employed in the past is the use of a regain indicator. This method does nothing to the cotton, but it provides a means for correcting the variation in weight due to difference in humidity.

The indicator consists of a balance similar to a scale balance. On one end of the balance a sample of cotton of known dry weight is hung. The opposite end of the balance arm constitutes a pointer back of which is located a percent regain scale. The scale is adjusted so as to indicate the correct regain as the humidity varies and induces moisture into the cotton sample.

While this method is used extensively, textile engineers are aware of the fact that it is only accurate so long as the outside humidity conditions are consistently the same as room conditions. There is no question that this is rare and that the method is subject to large amounts of error.

In accordance with my invention as distinguished from the prior art the moisture of the lap is measured as the lap is being produced, and my method comprises inti- Inately contacting the cotton itself as it leaves the picker, making use of the conventional rake which is a part of ex sting apparatus, the rake being included in an electrical circuit which also includes a measuring instrument serving to indicate percentage regain and through such instrument variations in the lap weight are determined.

The invention will be more readily understood by reference to the accompanying drawings and the following detailed description, in which a specific embodiment of the invention is set forth by way of illustration rather than by way of limitation.

In the drawings:

FIG. 1 is a side view, partly in section and largely diagrammatic in character, of the calender or delivery end of a picker and showing the rake with electrical connections indicated which are part of a circuit including an electrical measuring instrument not shown in this figure;

FIG. 2 is a diagrammatic view on a larger scale than FIG. 1 showing the rake electrically connected to the electrical measuring instrument which is indicated diagrammatically;

FIG. 3 shows a modified scale for the measuring instrument.

Referring to the drawings, the reference numeral denotes a conventional condenser gauge at the delivery end of a picker machine. A lap of partially cleaned cotton 11 moves through the condenser gauge between upper and lower stripper rolls 12 and 13, then beneath a rake 14 and thence between successive pairs of calender rolls 15, 16, 17 and 18, after which it passes under the guide roll 19 and onto suitably fluted calender rolls 2%, 21 which support the finished lap 22. A portion of the frame of the machine is indicated at 23.

The rake, which is a metal bar having fingers that press firmly against the lap as it passes from the stripper rolls 12, 12 to the calender rolls, is shown as carried by a bracket 24 mounted on the frame of the machine. The rake 14 is insulated from the frame, and to this end the bracket 24 may be of insulating material while the rake itself, including the fingers, is of suitable conducting material, as the rake and bracket both may be conductors and the bracket may be suitably insulated from the frame in any suitable manner. Leads 25 and 26 are connected to the rake 14 and to the frame respectively, and form part of an electrical circuit which includes the conductivity measuring instrument 27 which may be of the type disclosed in Heppenstall Patent No. 2,826,247, and in which any of the electrical circuits disclosed therein may be employed. It is not necessary to illustrate these circuits in the drawing as they are adequately disclosed in the patent referred to. As shown in FIG. 2 the dial 23 of the measuring instrument is calibrated in terms of moisture regain and it will be understood that any suitable measuring instrument calibrated in terms of moisture regain may be employed within the scope of the invention in its broadest aspects provided that the measuring circuit is properly damped so as to permit easily read indications, and provided also that the range of the instrument is adequate. While in FIG. 2 the dial or scale of the measuring instrument is shown in terms of moisture regain the scale may be otherwise calibrated, as shown for example in the scale 29 in FIG. 3, which may be substituted for the scale 28 of FIG. 2. In FIG. 3 the scale is shown as calibrated in terms of tare or the amount to be deducted from the gross weight found for each lap. It will be apparent that the type of scale must be designed for a particular lap, the present one being for a standard weight of pounds. In many instances this type of scale might be of greater value than the percentage regain scale of FIG. "2 since no weight calculations need be made by the picker operator.

The invention has been described in detail for the purpose of illustration but it will be obvious that numerous modifications and variations may be resorted to without departing from the spirit of'the invention.

1 claim:

A method for determining textile picker lap weights which comprises contacting the interior of a moving textile lap as it leaves the picker with a lap penetrating electrical conductor member included in an electrical circuit with an instrument for measuring variations in electrical conductivity corresponding to variations in moisture content at different portions of the lap, said conductor member including finger means penetrating the material of the moving lap.

References Cited in the file of this patent UNITED STATES PATENTS 2,528,342 Cuckler Oct. 31, 1950 2,542,331 Hiensch Feb. 20, 1951 2,587,771 Schoenbaum Mar. 4, 1952 2,626,423 Collins Ian. 27, 1953 2,703,386 Seney Mar. 1, 1955 FOREIGN PATENTS 569,439 Great Britain May 24, 1945 OTHER REFERENCES Cady: Moisture Meters Move Up, Scientific American, November 1946; pages 205-207. 

